The Session Initiation Protocol (SIP) is an application-layer control (signaling) protocol for creating, modifying, and terminating sessions with one or more participants. These sessions include Internet telephone calls, multimedia distribution, and multimedia conferences. SIP has been accepted as a 3GPP signaling protocol and is a permanent element of the IMS architecture. It is widely used as a signaling protocol for Voice over IP, along with H.323 and others. SIP is addressing neutral, with addresses expressed as URL/URIs of various types, such as e.g. telephone numbers, email addresses etc.
The IP Multimedia Subsystem (IMS) is a standardised Next Generation Networking (NGN) architecture for telecom operators that want to provide mobile and fixed multimedia services. It uses a multimedia signaling based on a standardised implementation of SIP, and runs over the standard Internet Protocol (IP). Existing phone systems (both packet-switched and circuit-switched) are supported.
Universal Plug and Play (UPnP) is a set of computer network protocols promulgated by the UPnP Forum. The goals of UPnP are to allow devices to connect seamlessly and to simplify the implementation of networks in the home (data sharing, communications, and entertainment) and corporate environments. UPnP achieves this by defining and publishing UPnP device control protocols built upon open, Internet-based communication standards. UPnP thus is a protocol for in-house/in-office networks, providing that devices are able to find each other and communicate with each other. UPnP, which is IP based, is very fit for interconnecting e.g. media players, TV's, printers, scanners, electric switches, dimmers, home automation devices etc. Some of the UPnP enabled devices could be remotely operated or set (e.g. the heating) via e.g. the Internet or another external network.
It is desirable to enable remote access to UPnP devices/services from a SIP device, e.g. a SIP/IMS based mobile terminal, via a SIP-UPnP gateway function.                Several prior art solutions have been proposed in the past, e.g.        Using SIP for building a UPnP Remote Access Tunnel;        Using SIP Message Services for transportation of UPnP messages (see WO 2006071468);        Using SIP for bridging to UPnP networks (WO/2007/002242).        
These prior art solutions for remote access to UPnP devices/services, disadvantageously, all require any adaptation of the SIP terminal to be used for remote access.
The document “Framework Draft for Networked Appliances using the Session Initiation Protocol” by S. Moyer et al., Internet Engineering Task Force Internet Draft, 2001, discloses the use of SIP for network-capable appliances.
Furthermore, different solutions for addressing the network elements for bridging SIP control messages to UPnP messages are available. Every UPnP address can be mapped on a SIP URI address. This solution is a very straightforward solution, but it requires one of the following two configurations:    1. All the SIP URI addresses are configured in the public network domain in the different SIP elements. Because UPnP devices can be dynamically added or removed from the UPnP network, this requires dynamic addition/removal of SIP URI addresses in the public network domain. Such a dynamic process does not exist and brings with it a lot of complexity for the SIP/IMS network domain administrator. Therefore, this is not a practical solution.    2. The UPnP domain has its own SIP address domain, e.g. UPnPbridgel.com. Each separate UPnP address is part of the address domain, e.g. UPnPdevicel@UPnPbridgel.com. While this certainly is a technically feasible solution, this requires that all UPnP/SIP bridges to be connected to the SIP network have to use a Network to Network Interface (NNI). This also brings a lot of complexity for the SIP/IMS network domain administrator, and is therefore not a practical solution
The prior art configurations require special/additional UPnP functionality to be installed in or added to the SIP terminal.
It is desirable to provide for a method and/or means aiming to enable standard (e.g. mobile) SIP terminals to be used to access and control UPnP devices and services via the SIP/IMS network.
Moreover, it may be desirable that dynamic configuration of SIP addresses in the SIP network or NNI-based interconnection of SIP/UPnP bridges with the SIP network are not required.